docs: def list_containers(self):
          """
          list all available nspawn containers
  
          :return: collection of instances of :class:`conu.backend.nspawn.container.NspawnContainer`
          """
          data = run_cmd(["machinectl", "list", "--no-legend", "--no-pager"],
                         return_output=True)
          output = []
          reg = re.compile(r"\s+")
          for line in data.split("\n"):
              stripped = line.strip()
              if stripped:
                  parts = reg.split(stripped)
                  name = parts[0]
                  output.append(self.ContainerClass(None, None, name=name))
          return output